Packaged semiconductor devices are currently handled and shipped in a variety of media. The predominant shipping medium for devices such as packages including those with a large numbers of leads or fragile leads is a tray composed of a support plate and a matrix of cells. Each cell is intended to contain one semiconductor device. In a typical handling procedure, shipping trays containing devices within the cells are stacked on top of each other with the top tray being empty and serving only as a lid. Many current configurations of semiconductor device packages are commonly handled and shipped in matrix trays. Examples of these packages commonly processed and shipped in trays include array package types and leaded package types. Array package types include ball grid array (BGA), quad flat package-no lead (QFN), and a pin grid array (PGA). Leaded package types include metric quad flat package (MQFP), thin quad flat package (LQFP), very thin quad flat package (TQFP), thin small outline package type I (TSOP-I), thin small outline package type II (TSOP-II), bumpered quad flat package (B/PQFP), and plastic leaded chip carrier (PLCC). Many trays have been standardized in the semiconductor industry, such as those know as JEDEC trays.
Although most trays have been standardized, numerous handling problems still exist with the use of currently available trays. A primary problem with existing trays is that they must be accurately loaded with the component in order function normally during processing/handling and shipping. Improperly loaded trays can cause poor mating between trays causing device damage during tray stacking, lack of adequate segmentation between cells which allows one device to migrate to an adjacent cell and damage the neighboring device, and insufficient device retention features in each cell allowing devices to break or override the retention features. These problems may be compounded in assembly/test development factories where material handling systems transfer large quantities of components from a matrix tray onto a pallet, and then back onto the matrix tray for further manufacturing and/or shipping steps.
Modern assembly lines use a variety of material handling systems or product transfer modules which have been designed to accurately transfer material to precise locations on the tray or substrate; however such transfer systems are highly complex and may require post-placement inspection to detect defects, misalignments, or components placed outside a predetermined tolerance. In-tray visual inspection and complex electrical tests to ensure accuracy are problematic in that they require advanced electronic equipment and software.
Other apparatuses have been designed to eliminate problems associated with misaligned components in the tray. For example, U.S. Pat. No. 5,492,223 relates to a tray for handling a semiconductor device encapsulated in a package having cell-to-cell interlocking capability. An interlocking nest feature is formed on the underside of the tray and interfaces with the cells on the topside of the tray when the trays are stacked. The interlocking nest feature has an external chamfer which mates with a lead-in chamfer of the tray cell to align the interlocking feature and the cell. The interlocking nest feature has an internal device retaining chamfer and a device capture surface to guide and retain the semiconductor device when stacking trays, inverting trays or processing semiconductor devices with the trays inverted. In-tray inspection and electrical test are also possible using a test contactor having a functional equivalent of the interlocking nest feature. However, this apparatus does not solve the problem of precisely loading the matrix tray in the first instance.
Accordingly there is a need to solve the problems associated with precision placement of parts especially during high volume assembly, quality control, and shipping of semiconductor components. Furthermore, there is a need to improve state-of-the art material transfer handling systems by reducing the necessity for high precision electronics, and precision programming necessary to operate the equipment. Thus, it is desirable to have a device which addresses all of the aforementioned problems and limitations found in the current material handling systems.